DE2607541A1 - PHOTOGRAPHIC CAMERA WITH AN ELECTRONIC EXPOSURE CONTROL DEVICE - Google Patents

Description

Kodak Corporation
7000 Stuttgart - Wangen
P.O. Box 369

III6 Lev / En 2k. February 1976

Patent application

Photographic camera with an electronic exposure control device

The invention relates to a photographic camera with an electronic Exposure control device and with a flash device, wherein the exposure control device forms both the daytime exposure time and the flash exposure time.

In photographic cameras of this type, depending on the intensity of the object illumination, the shutter is both in daylight as well as in flash light after the passage of an amount of light that is decisive for a correct exposure of the film closed. This shutter control takes place via an exposure control device, which is equipped with a fast-switching light converter, e.g. a silicon cell. at When the shutter closes, there is a time delay between the electrical signal for closing the closure (end of time formation) and the actual closing process (closed state of the closure members). The reason for the time lag lies in the mass

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inertia of the mechanical locking links. When the beginning the timing and the start of opening of the closure members take place at the same point in time, accordingly closes the closure with a time delay, which results in overexposure of the film.

In daylight operation, this error is compensated for by changing the time at which the electronic time calculation starts by the im significant constant time error is brought forward, i.e. the time calculation starts around the time span of the time error before Beginning of shutter opening. This measure is possible because in daylight operation with every exposure process (recording) constant object illumination can be assumed.

In flash mode, this exposure time error cannot be compensated in the manner described above, because with the Flash light emitted by an artificial light source cannot achieve constant object illumination. This means, bringing forward the start of time formation with respect to the shutter opening process does not compensate for the Time error because the due to the non-linear course of the flashlight curve at the beginning of the flash firing about a certain The amount of light emitted is not the same and also not proportional to the amount of light emitted at the end of the flash ignition via the the same amount of light emitted.

The invention is based on the object of providing a camera of the type mentioned at the outset in a simple and sufficiently precise manner Way to enable the compensation of the timing error in flash operation.

According to the invention, this is achieved in that for compensation an exposure error that occurs when the shutter is closed compared to the termination of the electronic timing

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In the case of flash operation, a diaphragm element that can be switched on to a lens diaphragm is provided, the diaphragm opening of which has a according to the exposure time error to be compensated

Has changed shape and is controllable as a function of distance.

So that the compensation of the exposure time error can take place continuously, the diaphragm element has a diaphragm opening Form of a drop aperture. The shape of the drop diaphragm is determined in accordance with the timing error.

In this simple manner, one becomes sufficient when the flash is operated accurate compensation of the exposure time error achieved.

The other features and advantages of the invention are described below one embodiment shown in the drawing and the other claims. the Drawing shows in the

Fig. 1 shows the essential components of a photographic camera relating to the aperture device and the inventive device Diaphragm element in a schematic representation,

2 shows a time diagram of a closure,

3 shows a time diagram of a flash light curve and FIG

4 shows a time diagram of a capacitor of the exposure control device for daylight mode and for flash light mode.

The embodiment is a camera of the self-developer type, which has an electronic exposure

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control device as well as a fitting to accommodate multiple flash units and to accommodate computer electronic flash units disposes.

The camera essentially consists of an objective carrier 11 connected to the camera housing, the light inlet opening of which forms a fixed aperture 12 (for example aperture 11). An annular diaphragm adjuster with a ring toothing 13 is rotatably arranged on the objective carrier 11. The ring toothing 13 meshes with a further gear Ik which carries a curve 15 which is used for distance-dependent control of a diaphragm element 16 during flash operation with non-electronic flash units, eg with electrically ignitable multiple flash units.

The diaphragm member 16 can be pivoted about an axis 17 fixed to the housing stored and designed as a double lever. If the diaphragm member 16 is out of operation, it rests against a stop at. The end of one arm, which can be pivoted into the area of the fixed aperture 12, is open on one side Drop aperture 19 formed. The end of the other arm of the diaphragm member 16 has an angled portion 20 which extends below the force of a spring 21 is supported on the curve 15.

A control lever 22 which is mounted pivotably about an axis 23 is, holds the diaphragm member 16 in its initial position. A feather 25 pulls the control lever 22 against the angle 26 of a feeler lever 24, which is supported by a spring 27 about an axis 34 in its Initial position is forced, in which it rests against a projection 28 of a closure plate.

Furthermore, a switch is in the range of motion of the touch lever 24 32 arranged, which is in the circuit of a light emitting diode to display the minimum lighting for handheld photography.

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It is a further screen device 29 for daylight operation with an opening 30 (e.g. diaphragm 16) smaller than the fixed diaphragm opening 12, which during daylight operation can be pivoted in via the aperture 12 in the case of very bright object lighting. For this purpose it is dependent a magnet excited or not excited by an electronic exposure control device and thus a locking member 31 controlled out of or in the path of the diaphragm device 29. A window 33 in the diaphragm device 29 is a light inlet opening 34 for the photosensitive element, which consists of a silicon cell consists of the electronic exposure control device assigned.

The mode of operation of the subject matter of the invention is described using three camera states:

1. daylight operation,

2. Flash operation with non-electronic flash unit and

3. Flash operation with electronic flash unit.

In daylight operation, when no flash unit is plugged into a socket provided for this purpose on the camera housing , the touch lever 24 and thus the diaphragm element 16 are not actuated. The diaphragm member 16 is held outside the diaphragm opening 12 by the control lever 22. The diaphragm element 16 is also not influenced when setting the distance. The aperture is formed as a function of the electronic exposure control device via a magnet and the blocking element 31 controlled by the same by means of the aperture device 29. The switch 32 for indicating a possible underexposure remains closed.

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The time delay between that of the exposure control device that occurs as a result of the inertia of the shutter members output electrical signal for closing the shutter and the actual closing process of the shutter members , which is approximately 5 milliseconds in the exemplary embodiment, is brought forward by bringing the start of the time formation forward compensated for this error of .5 milliseconds (see Fig. 2).

In the case of flash operation, the compensation of the by the shutter members caused time delay in the manner described above due to the non-constant object illumination however, cannot be carried out. Since the time formation (shutter open position) depends on the charging process of a capacitor, which is switched on in the light measuring circuit of the silicon cell, the same is terminated when one for the Correct exposure of the film, sufficient amount of light has been measured. The electronic exposure control device gives the signal to close the shutter is released immediately, but it is delayed by about 5 milliseconds, in its closed position. In daylight operation, the capacitor is charged, i.e. the time is calculated or integration, steadily as a result of constant object illumination (see FIG. 4). Charging takes place in flash mode of the capacitor, however, according to the course of the flashlight curve (see FIG. 3) »qualitatively according to that in the Fig. 4 shown dashed curve. From Fig. 3 it can be clearly seen that the amounts of light emitted by the flash light completely different over the same time periods of about 5 milliseconds at the beginning of the flash curve and at the end of the same are, so that a compensation of the temporal error by bringing forward the start of timing is not possible is.

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According to the invention, there is now an almost common starting time assumed for the beginning of time formation (beginning of integration) and the beginning of the shutter opening and that at the end of the Exposure errors occurring over time as a result of the shutter inertia compensated by a second diaphragm element, which is superimposed on the aperture 12 of the lens. As the lighting intensity of the flash light also depends on the object distance, this diaphragm element 16 is equipped with a distance adjuster coupled.

When operating the flash with an electrically ignitable multiple flash unit plugged into the socket, the base of the flash unit, the scanning lever 24 is pivoted from its starting position into position "A". The twisted Touch lever 24 with its angle 26 the control lever 22 so far that the diaphragm member 16 with its bend 20 on the curve 15 comes to rest and over the entire stroke of the curve 15 can follow the same. Depending on the distance setting The drop diaphragm 19 pivots continuously into the region of the diaphragm opening 12 of the objective and covers the same more or less. This way the exposure error becomes compensated due to the shutter inertia during flash operation.

At the same time, when the tactile lever 24 is depressed, the underexposure switch becomes 32 open so that no underexposure display can take place when the flash is in operation.

The diaphragm device 29 for daylight operation is located in that shown in FIG. 1, depending on the outside illumination Position (dark object) or in the position covering the aperture 12 (light object).

When the subject is brightened by a flash in bright outside light, e.g. when taking backlit photos, the aperture is opened

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the diaphragm device 29 effective. When operating the flash with an electronic flash unit, the scanning lever 24 is removed from the base of the flash unit is pivoted, but by a smaller amount, until it reaches position "B". This movement of the Sensing lever 24 is sufficient to open the underexposure switch 32, so that no underexposure display when using the camera connected electronic flash unit can take place. The diaphragm member 16 is not released and can therefore at do not follow the distance setting of curve 15. That means, the working aperture for flash operation with an electronic flash unit is aperture value 11, depending on the outside lighting (Aperture 12) or aperture value 16 (aperture 30). The amount of light is dosed by the flash unit self.

In order to achieve an optimal exposure of the film, further time or light-dependent factors are taken into account, such as the Schwarzschild effect, i.e. the change in DIN sensitivity with different exposure times of the film.

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Claims (1)

Claims fly photographic camera with an electronic exposure control device and with a flash device, wherein the exposure control means forms both the daytime exposure time and the flash exposure time, thereby characterized in that to compensate for a ^ when closing of the shutter compared to the termination of the electronic time formation, the exposure time error that occurs during flash operation a diaphragm element which can be connected to an objective diaphragm is provided, the diaphragm opening of which is one according to the specifications the exposure time error to be compensated Has changed shape and can be controlled depending on the distance is. 2. Photographic camera according to claim 1, characterized in that that for stepless compensation of the exposure time error the aperture (19) of the diaphragm member (l6) the Has the shape of a drop aperture. 3. Photographic camera according to claims 1 and 2, characterized in that the diaphragm member (16) as a pivotable Wing diaphragm is designed in the form of a two-armed lever, and that at the end of one arm, the aperture opening (19) is located and the end of the other arm of the curve (15) of the distance adjuster is assigned. M. Photographic camera with an electronic exposure control device with a function of the object illumination electromagnetically controllable diaphragm device for daylight operation as well as with a flashlight device, in particular according to claim 1, characterized - 10 709835/0238 -> Ö - net that the provided in addition to the diaphragm device (12,29) and the diaphragm element (16) which cannot be influenced by the electromagnet only when the flash device is operatively connected to the camera is coupled to a distance adjuster, 5 · Photographic camera according to one or more of Claims 1 to 4, characterized in that in operation with the camera connected electrically or piezo-electrically ignitable flashlight device, the diaphragm element (l6) with a The curve (15) of the distance adjuster is coupled, but not coupled when the electronic flash unit is connected to the camera is. 6. Photographic camera according to one or more of claims 1 to 5, characterized in that each type of with the Camera operatively connected flash device an underexposure signal device is out of service. 7. A photographic camera according to one or more of claims 1 to 6, characterized in that one of one with the camera Operationally connected flashlight device controlled tactile lever (24) is provided, the one in the circuit of the Underexposure signal device located switch (32) actuated. 8. Photographic camera according to one or more of the claims 1 to 7, characterized in that by means of the feeler lever (24) directly or via a control lever (22) the diaphragm element (16) can be coupled to the curve (15) of the distance adjuster is. 709835/0238